The invention relates to metal oxide powders. More particularly, the invention relates to nanoscale metal oxide particles, such as manganese oxide particles, produced by laser pyrolysis. The invention further relates to methods for producing metal oxide powders with laser pyrolysis and aerosol precursors.
Advances in a variety of fields have created a demand for many types of new materials. In particular, a variety of chemical powders can be used in many different processing contexts. Specifically, there is considerable interest in the application of ultrafine or nanoscale powders that are particularly advantageous for a variety of applications involving small structures or high surface area materials. This demand for ultrafine chemical powders has resulted in the development of sophisticated techniques, such as laser pyrolysis, for the production of these powders.
Manganese can exist in various oxidation states. Correspondingly, manganese oxides are known to exist with various stoichiometries. In addition, manganese oxides with a particular stoichiometry can have various crystalline lattices, or they can be amorphous. Thus, manganese oxides exhibit an extraordinarily rich phase diagram.
Manganese oxides with various stoichiometries have been noted as promising materials for use in lithium based batteries. Appropriate manganese oxides can intercalate lithium ions into their crystal structure. Because of the interest in manganese oxides, several approaches have been developed for producing manganese oxides. Other metal oxide powders are useful in the production of batteries as well as a variety of other applications.
In a first aspect, the invention pertains to a collection of particles comprising manganese oxide, the collection of particles having an average diameter less than about 500 nm, the manganese oxide having a structure selected from the group consisting of amorphous manganese oxide, crystalline MnO, crystalline Mn5O8 and crystalline Mn2O3.
In another aspect, the invention pertains to a method of producing a metal oxide powder, the method comprising reacting an aerosol within a reaction chamber to form metal oxide particles, the aerosol comprising a metal precursor and the metal oxide particles having an average diameter less than about 500 nm.
In a further aspect, the invention pertains to a method for altering the stoichiometry of a collection of manganese oxide particles, the method comprising heating manganese oxide particles in an oxidizing environment at a temperature less than about 600xc2x0 C.
In another aspect, the invention pertains to a battery having a cathode comprising manganese oxide particles, said manganese oxide particles having an average diameter less than about 250 nm.